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Subject[PATCH 4.4 048/118] cpuset: make sure new tasks conform to the current config of the cpuset
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Zefan Li <lizefan@huawei.com>

commit 06f4e94898918bcad00cdd4d349313a439d6911e upstream.

A new task inherits cpus_allowed and mems_allowed masks from its parent,
but if someone changes cpuset's config by writing to cpuset.cpus/cpuset.mems
before this new task is inserted into the cgroup's task list, the new task
won't be updated accordingly.

Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
kernel/cpuset.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)

--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -2074,6 +2074,20 @@ static void cpuset_bind(struct cgroup_su
mutex_unlock(&cpuset_mutex);
}

+/*
+ * Make sure the new task conform to the current state of its parent,
+ * which could have been changed by cpuset just after it inherits the
+ * state from the parent and before it sits on the cgroup's task list.
+ */
+void cpuset_fork(struct task_struct *task)
+{
+ if (task_css_is_root(task, cpuset_cgrp_id))
+ return;
+
+ set_cpus_allowed_ptr(task, &current->cpus_allowed);
+ task->mems_allowed = current->mems_allowed;
+}
+
struct cgroup_subsys cpuset_cgrp_subsys = {
.css_alloc = cpuset_css_alloc,
.css_online = cpuset_css_online,
@@ -2084,6 +2098,7 @@ struct cgroup_subsys cpuset_cgrp_subsys
.attach = cpuset_attach,
.post_attach = cpuset_post_attach,
.bind = cpuset_bind,
+ .fork = cpuset_fork,
.legacy_cftypes = files,
.early_init = 1,
};

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